Protect people and report the collision
Move out of active traffic when doing so is safe and lawful, call 911 for injuries or hazards, and follow directions from law enforcement. Do not delay emergency care to collect evidence. A police report does not by itself decide civil liability, but it can preserve names, scene observations, vehicle information and an incident number.
New or worsening symptoms deserve medical attention. Some neck, back, head and soft-tissue injuries are not fully apparent at the scene. Describe symptoms accurately and follow the treatment plan given by qualified health professionals.